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International Journal of Bioinformatics and Biological Science: v.1 n.1 p.71-77. March, 2013 Antimicrobial properties of tea tree oil
Puja Kumari
Jacob School of Biotechnology and Bioengineering, SHIATS, Allahabad, UttarPradesh, India *Corresponding Author: Puja Kumari pkumari402@gmail.com ABSTRACT
Phytomedicine such as tea tree (melaleuca) oil have become increasingly popularin recent decades. This essential oil has been used for almost 100 years in Australiabut is now available worldwide both as neat oil and as an active component in anarray of products. The primary uses of tea tree oil have historically capitalized onthe antiseptic, antifungal, antiviral and anti-inflammatory actions of the oil. Reportsof activity in the field of antibacterial Tea tree oil research are widely conflicting,probably owing to inter- and intra-assay variation in susceptibility testing. However,several high-quality investigations have examined the relationship betweencomponent structure and antibacterial activity and these are in close agreement.
The mechanism of action of tea tree oil and three of its components, 1,8-cineole,terpinen-4-ol, and alpha terpineol, against Staphylococcus aureus wereinvestigated. In addition, numerous research groups have sought to elucidate theantibacterial mechanisms of action of selected components of tea tree oil. Thesecompounds represent novel leads, and future studies may allow the developmentof a pharmacologically acceptable antimicrobial agent or class of agents. Thisreview summarizes recent developments in our understanding of the antimicrobialactivity of the oil. Specific mechanisms of antibacterial activity are reviewed, andthe toxicity of the oil is briefly discussed.
Keywords: Tea tree oil, Antibacterial activity
BACKGROUND
Resistance to antimicrobial agents has become an increasingly day by day and it isa problem of global concern. Of the 2 million people who acquire bacterial infectionsin US hospitals each year, 70% of cases now involve strains that are resistant to atleast one drug. A major cause for concern in the UK is methicillin-resistant Staphylococcus aureus (MRSA), which was at low-level a decade agobut now accounts for ca.50%of all S. aureus isolates(Adock 2002). Substantialinvestment and research in the field of anti-infective are day now desperately neededif a public health crisis is to be averted.
Tea tree oil, or melaleuca oil, is a pale yellow color to nearly colorless andclear essential with a fresh camphoraceous odor(Directory of essential oils forAromatherapy). It is taken from the leaves of the Melaleuca alternifolia, which isnative to Southeast Queensland and the Northeast coast of New, Australia. Tea tree oil should not be confused with tea oil, the sweet seasoning and cooking oil frompressed seeds of the tea plant Camellia sinensis (beverage tea), or the tea oilplant Camellia oleifera. The indigenous Bundjalung people of eastern Australia use“tea trees” as a traditional medicine by inhaling the oils from the crushed leaves totreat coughs and cold. They also sprinkle leaves on wounds, after which a poultice isapplied. In addition, tea tree leaves are soaked to make an infusion to treat sorethroats or skin ailments(Shemesh and Mayo ,1991 and Low ,1990). Use of the oilitself, as opposed to the unextracted plant material, did not become common practiceuntil researcher Arthur Penfold published the first reports of its antimicrobial activityin a series of papers in the 1920s and 1930s. In evaluating the antimicrobial activityof M. alternifolia, tea tree oil was rated as 11 times more active than phenol(Penfoldand Grant ,195). The commercial tea tree oil industry was born after the medicinalproperties of the oil were first reported by Penfold. Production ebbed after WorldWar II, as demand for the oil declined, presumably due to the development ofeffective antibiotics and the waning image of natural products. Interest in the oilwas rekindled in the 1970s as part of the general renaissance of interest in naturalproducts. Commercial plantations were established in the 1970s and 1980s, whichled to mechanization and large-scale production of a consistent essential oilproduct(Johns et al ,1992).
Among over 98 compounds contained in the oil, terpinen-4-ol is responsible formost of the antimicrobial activity(Hart et al ,2000).Tea tree oil is defined byinternational standard ISO 4730 (2004) (“Oil of Melaleuca, Terpinen-4-ol type”),which specifies levels of 15 components which are needed to define the oil as “teatree oil.” TTO has a relative density of 0.885 to 0.906 is only sparingly soluble inwater, and is miscible with non polar solvents((IOS) Medicinal properties of Tea tree oil
Increasingly, Tea tree oil is becoming the subject of medical research. They havebeen reported to possess many useful properties, including, antiviral (Schnitzler etal ,2001)antibacterial, antifungal and antiseptic qualities. It also has beneficialcosmetic properties(Aburjai and Natsheh ,2003).The active ingredients of Melaleucaalternifolia (or Tea Tree) oil are terpinen and cineole. Terpinen is the ingredientresponsible for the healing properties. Cineole contributes the disinfectant properties.
In large amounts, cineole is caustic to human tissue. In order to obtain the bestresults from using tea tree oil, the percentage of terpinen must be between 35 and60 percent, and the percentage of cineole must be below ten percent to ensure skinsafety during usage (Figure 1).
Tea tree oil is also effective as an additional treatment for colds, bronchitis, whoopingcough and pneumonia. Adding it to a vaporizer and inhaling the fumes helps to killgerms that infect the sinuses and lungs. Similar to eucalyptus oil, tea tree oil alsoopens clogged respiratory passages. It has been suggested for some time that teatree oil may be an effective agent for both the treatment and prevention of oral International Journal of Bioinformatics and Biological Science: v.1 n.1 p.71-70. March, 2013 In vitro studies show the effectiveness of tea tree oil in inhibiting several commonskin pathogens. Terpinen-4-ol and whole tea tree oil were found equally effectivefor activity against Staphylococcus aureus(Williams et al ,1997) Raman andassociates tested several major components of tea tree oil (terpinen-4-ol, alpha-terpineol, alpha-pinene, and cineole) for their effects against S. aureus,Staphylococcus epidermidis, and Propionibacterium acnes(Raman et al,1995) Except for cineole, all of the constituents tested were inhibitory to all threeorganisms.
Toxicity of tea tree oil
When ingested, tea tree oil may cause abdominal pain, diarrhea, confusion,drowsiness, lethargy, uncoordinated walking, depressed immune function and coma.
Tea tree oil used as a mouthwash may alleviate symptoms of gingivitis or thrush, ayeast infection of the mouth; it cautions that swallowing any amount of tea tree oilis toxic. Exercise discretion when using any mouthwash containing tea tree oil toavoid oral toxicity. The American Cancer Society cautions that tea tree oilpreparations should not be used in children or if you are a woman who is pregnantor breastfeeding.
Recent evidence has demonstrated that exposure to tea tree oil can lead to allergiccontact dermatitis in susceptible individuals. At the Skin and Cancer Foundation inSydney, Australia, three of 28 normal volunteers were positive to patch testing withtea tree oil(Rubble et al ,1998). Further testing of tea tree oil constituents showedthat all three patients were responding to the sesquiterpenoid fraction of the essentialoil. In an earlier study, seven patients who had become sensitized to tea tree oilwere exposed to 1% tea tree oil and 1% solutions of 11 isolated individualconstituents(Knight et al ,1994) Of the seven patients who reacted to 1% tea treeoil, six also reacted to limonene, five to alpha-terpinene and aromadendrene; tworeacted to terpinen-4-ol and one each to p-cymene and alpha-phellandrene. Thesereports indicate that several components of tea tree oil are capable of causing allergicskin reactions.
Antimicrobial action of tea tree oil
The mechanism of action of TTO against bacteria has now been partly elucidated.
Prior to the availability of data, assumptions about its mechanism of action weremade on the basis of its hydrocarbon structure and attendant lipophilicity. Sincehydrocarbons partition preferentially into biological membranes and disrupt theirvital functions(Sikkema et al,1995) TTO and its components were also presumedto behave in this manner. This premise is further supported by data showing thatTTO permeabilize model liposomal systems .In previous work with hydrocarbonsnot found in TTO and with terpenes found at low concentrations in TTO lyses andthe loss of membrane integrity and function manifested by the leakage of ions and International Journal of Bioinformatics and Biological Science: v.1 n.1 p.71-77. March, 2013 the inhibition of respiration were demonstrated. Treatment of S. aureus with TTOresulted in the leakage of potassium ions and 260-nm-light-absorbing materialsand inhibited respiration. Treatment with TTO also sensitized S. aureus cells tosodium chloride and produced morphological changes apparent under electronmicroscopy.
In summary, the loss of intracellular material, inability to maintain homeostasis,and inhibition of respiration after treatment with TTO and/or components is consistentwith a mechanism of action involving the loss of membrane integrity and function.
The antimicrobial activity of TTO against those bacteria which are antibiotic-resistant has attracted considerable interest, with methicillin-resistant Staphylococcus aureus (MRSA) receiving the most attention thus far. Sinceusing TTO against MRSA was first hypothesized(Walsh and Longstaff,1987) severalmembers have demonstrated the activity of TTO against MRSA, started with (Carsonet al,1995) who examined 64 MRSA isolates from Australia and the UnitedKingdom, including 33 Mupirocin-resistant isolates. The MICs and minimalbactericidal concentrations (MBCs) for the Australian isolates were 0.25% and0.5%, respectively, while those for the United Kingdom isolates were 0.312% and0.625%, respectively. In another studies tea- tree oils, terpinen-4-01, α-terpineol and a-pinene were found to be active against Staphylococcus aureus,Staphylococcus epidermidis and Propionibacterium acnes whereas cineole was inactive against these organisms(Raman et al,1995 and Gibbons 2004) whoexamined 1, 8-cineole exhibits little antimicrobial activity inherently, however, ithas been shown to enhance the lethal action of terpinene. It is hypothesized that 1,8-cineole helps permeabilize bacterial membranes, allowing more active terpinento enter and kill the bacterial cell( Mehrotra et al2010). demonstrated the comparativeantimicrobial activities of neem, amla, aloe, Assam tea and clove extracts againstvibrio cholera, Staphylococcus aureus and pseudomonas aeruginosa.
Assay of antimicrobial activity of essential oil like lemon grass, oregano,tea tree against Enterococcus fecalis, Escherichia coli, Klebsiella pneumonia,and Staphylococcus aureus at d” 2.0% by using an agar dilution method(Hammeret al ,1999). Further Chao has also been demonstrated(Chao et al ,2008) a significantzone of inhibition [45-57 mm] for thyme, cumin, eucalyptus, cetriodora, tsuga,oregano, melaleuca alternifolia and limette essential oils. Bosnic et al. whoexamined antibacterial potential of Melaleuca alternifolia (tea tree) oil and membersof the Myrtaceae family, against strains of Staphylococcus aureus especially MRSA,exhibiting zones of inhibitions ranging from 10-45mm.
Carson et al. investigated the mechanism of action of Melaleuca alternifolia (Teatree) oil on Staphylococcus aureus determined by time kill, lyses, leakage, and salttolerance assays and electron microscope. Mann et al critically reviewed thetechniques used for determining the comparative anti-microbial properties of teatree oils. They note that most methods rely on Tween as a dispersant, which International Journal of Bioinformatics and Biological Science: v.1 n.1 p.71-70. March, 2013 underestimates the MIC of tea tree oil. Since producing reliable data in this area isrequired for registration of the oil as a therapeutic agent, they developed a newmicro-dilution method based on the redox dye resazurin using 0.15%w/v agar tostabilize and provide adequate contact between oil and test organism. Subsequentreports on the susceptibility of MRSA to TTO have similarly not shown greatdifferences compared to antibiotic-sensitive organism(Chan et al,1998,Elsom etal,1999,Hada et al 2001,May et al,2000 and Nelson 1997).
Mode of action of essential oil to target site’→ Disruption of cell wall’! Loss of
membrane integrity’→ Inhibition of cell respiration’! Blockage of DNA synthesis.
Figure 1: Flow Chart for Tea tree oil
CONCLUSION
Despite some progress, there is still a lack of clinical evidence demonstrating efficacyagainst bacterial, fungal, or viral infections. Large randomized clinical trials arenow required to cement a place for TTO as a topical medicinal agent. It is clearfrom the literature that Tea tree oil does have beneficial medicinal properties, relevantto the needs of modern populations. Future research should be directed to this goal.
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